The original MKI Magic Pie had the conventional crossed spokes:
If your wheel has the irregular hole spacing on the hub flange
(no crossed spokes) it will be an MPII.
The MPII is on the left, and the MPIII is on the right:
If you can find a 36 hole 30mm deep "V" rim, it should be OK to use your existing spokes:
However, if the internal diameter of the new rim is more than 2mm larger
(or smaller) than the GM rim you may need to use longer
(or shorter) spokes.
For example, if the internal diameter was 10mm larger, you would need spokes at least 5mm longer than the existing ones.
Alan